In the turbine art the practice is to produce a gas under pressure that is moved against the blades of a turbine wheel to produce mechanical rotary motion. Some prior known engines of this type ignite an airfuel mixture to drive a turbine wheel. U.S. Pat. No. 972,624 is an example of an early approach to this type of engine. The use of two axially-spaced turbine wheels is illustrated in U.S. Pat. No. 1,348,103 wherein, as the rotor revolves, the vanes suck an explosive charge through a shaft into an explosive mixture compression chamber and then into a combustion chamber using radial vanes and relatively complex valving. The engine of the present invention does not require preliminary compression of the air in a compression chamber and provides a number of improvements and advantages over the above-noted prior art, as will be apparent from a reading of the following detailed description.